Boston bomb suspect conscious and responding to questions

The 19-year-old is responding sporadically in writing to questions from investigators regarding other cell members and other unexploded bombs, law enforcement sources told ABC News.

The news comes as it is revealed Tsarnaev, who is badly wounded in the throat, meekly pulled up his shirt to show officers that he was not wearing a vest strapped with explosives on Friday night as he emerged from the boat he had been cowering in.

'At the end they were just making demands of him: Show your hands, lift your shirt. And eventually that's what he did,' Watertown Police Chief Edward Deveau told ABC News.

'He was very slow and lethargic in every move that he made and they could see that there was no device on his chest. They kept creeping closer to him and then they felt it safe enough to pull him away from the boat.'

Authorities initially said they couldn't question the terror suspect because of his severe throat wound.

Tsarnaev is believed to have shoved his pistol in his own mouth and pulled the trigger in a failed suicide attempt as SWAT officers and federal agents closed in on his backyard hiding place. However, instead of killing him, the bullet simply tore through his neck.

CNN reported earlier today that Tsarnaev was 'intubated and sedated' at a Boston hospital.